tbuckley/cabot-search huggingface dataset:
P844: GLOBAL CHARACTERIZATION OF MONOCYTE REVEALS A STRESS SIGNATURE INDUCED BY MULTIPLE MYELOMA BY SINGLE-CELL RNA SEQUENCING
Authors: Jian Cui, Wenqiang Yan, Jingyu Xu, Lugui Qiu, Gang An
Journal: HemaSphere (2023)

Topic: 13. Myeloma and other monoclonal gammopathies - Biology & Translational Research Background: A growing body of evidence has indicated impaired function or compositional changes of monocytes in inflammatory disorders, such as acute respiratory syndrome and covid-19. In myeloma tumor microenvironment, activation of type I interferon pathway and dysregulated expression of major histocompatibility complex type II genes are observed in classical monocytes, which result in loss of antigen presentation of monocytes. The proportions of BAFF+PD-L1+ monocytes in the bone marrow also correlate with survival of myeloma patients following chimeric antigen-receptor T cell therapy. Nevertheless, the mechanisms underlying PB and BM monocytes defects in myeloma remain poorly addressed, at least in part by the lack of large scale scRNA-seq studies. Aims: To resolve the heterogeneous bone marrow and peripheral blood monocyte subpopulations and their transcriptional factors between healthy donors and multiple myeloma patients. Methods: We conducted scRNA-seq on monocytes of 7 newly diagnosed myeloma patients and 12 healthy donors. Specifically, 3 and 5 bone marrow aspirates and 9 and 7 peripheral blood samples of 12 healthy controls and 7 newly diagnosed patients were obtained, respectively. Results: Heterogeneous bone marrow and peripheral blood monocyte subpopulations and their transcriptional factors were resolved. The function characteristics of monocyte were compared between MM patients and healthy donors, which indicated a stress signature induced by multiple myeloma. Furthermore, we identified two monocyte differentiation pathways, and discovered that bone marrow monocyte feature type I IFN-associated differentiation dysregulation in patients with MM as well as dysregulated patterns at transcriptome. Finally, we included 10 MM patients as a validation cohort, by tracking the stress signature over time in those patients undergoing first-line treatment, we founded that the stress signature was partially overcome by antitumor therapy. Summary/Conclusion: Our results provided further insight into transcriptional and differentiation changes occurring in the bone marrow and peripheral blood monocytes from patients with multiple myeloma and hint and mechanisms of immune evasion.Keywords: Monocyte, Multiple myeloma, RNA-seq, Microenvironment
PB1801: MYCN IS REQUIRED FOR MAINTAINING AN ONCOGENIC CHARACTERISTICS OF LEUKEMIA CELLS IN ACUTE MYELOID LEUKEMIA
Authors: Nanfang Huang, Yang Song, Qi He, Lingyun Wu, Zheng Zhang, Juan Guo, Chunkang Chang, Feng Xu
Journal: HemaSphere (2023)

Topic: 3. Acute myeloid leukemia - Biology & Translational Research Background: MYCN is a member of the MYC proto-oncogene family that also includes MYC and MYCL. Overexpression of MYCN is frequent in several solid cancers and associated with poor prognosis. However, the role of MYCN in acute myeloid leukemia (AML) remains poorly understood. Aims: To investigate the mechanism of MYCN in maintenance of malignant characteristic of leukemia cells. Methods: The expression of MYC family was analyzed in 542 AML patients, 76 chronic myeloid leukemia (CML) patients and 74 non-leukemia/healthy controls from Microarray Innovations in Leukemia (MILE) study. Lentivirus-mediated MYCN knockdown was performed to investigate its biological function in leukemia cell lines. The mechanism of MYCN in leukemia development was investigated by functional experiments. Results: We found that MYCN, not MYC or MYCL, was up-regulated in the AML patients compared with CML or non-leukemia controls. In vitro experiments, knockdown of MYCN impaired growth capacity, elevated autonomously cell apoptosis and increased apoptosis sensitivity to cytotoxic agent. Gene microarray and bioinformatic analysis suggested that MYCN plays a critical role in transcription regulation and apoptosis pathway. Correlation analysis and functional experiments revealed that MSI2 is a target of MYCN. Knockdown of MYCN inhibited the expression of MSI2. Mechanistically, MYCN could directly bind at the promoter of MSI2 and promote its transcription. Summary/Conclusion: MYCN oncogene contributes to the malignant characteristics of leukemia cells through activation of MSI2 in AML. MYCN is required for maintaining an oncogenic characteristics of leukemia cells in acute myeloid leukemia This study was supported by the National Natural Science Foundation of China (Grant No. 81770120 and 81770122) The authors declare no competing financial interests. Keywords: Acute myeloid leukemia, MYC, Oncogene
PB1749: COMPARATIVE STUDY OF B AND T-ALL IN CHILDREN, ADOLESCENTS, AND YOUNG ADULTS: CLINICAL CHARACTERISTICS AND THERAPEUTIC RESULTS
Authors: Imen Frikha, Aicha Ben Kahla, Moez Medhaffer, Nour Louati, Imen Ben Amor, Olfa Kassar, Latifa Khalifa, Maha Charfi, Faten Kallel, Rahma Mallek, Sondes Hdijji, Ikram Ben Amor, Hela Mnif, Moez Elloumi
Journal: HemaSphere (2023)

Topic: 2. Acute lymphoblastic leukemia - Clinical Background: Acute lymphoblastic leukemia (ALL) is the most common malignancy in children. This tumor has a good prognosis with cure rates of more than 80%. Therefore, epidemiological and therapeutic differences exist in terms of the phenotyping of ALL. The comparative analysis of B ALL and T ALL allowed a better differentiation of their characteristics as well as their evolution after treatment. Aims: The aim of this study is to compare the characteristics of B and T-ALL and predict the prognosis of these groups and their evolution after treatment. Methods: In this study, we enrolled retrospectively all cases of patients under 30 years old, with ALL diagnosed in the hematology department of Hedi Chaker Hospital, Sfax, Tunisia, between January 2000 and December 2021. The therapeutic protocol is EORTC 58951. We compared the epidemiological characteristics of B and T-ALL (age, sex, clinical and biological characteristics). We also compared the therapeutic outcomes of each phenotype of ALL: complete remission (CR), relapse rate, overall survival (OS), and event-free survival (EFS). Results: The comparative results of T and B-ALL were shown in the bellow table. - Characteristics TotalN= 395 LAL BN= 265 (67%) LAL TN=130 (33%) p Median age(years) 9 (1- 30) 7 (1-30) 13 (2-30) - Sex-ratio 1.58 1.38 2.1 - Tumor syndrome 297 (75%) 184 (71) 113 (88) <0.001 WBC ≥100G/L 74 (19%) 27 (10) 47 (36) <0.001 Corticoresistance 86 (22) 36 (14) 50 (38) <0.001 Complete remission 354 (90) 242 (91) 112 (86) <0.001 Failure remission 25 (6.5) 15 (6) 10 (8) - Relapse rate 116 (33) 86 (35) 30 (27) 0.084 OS at 5 years 63% 67% 54% 0.002 EFS at 5 years 58% 60% 53% 0.048 Summary/Conclusion: The frequency of T-ALL in our study (33%) is higher than those described in the literature (10 to 15%). The clinical and biological data of T-ALL in our study are characterized by more tumor syndrome and higher hyperleukocytosis than 100 G/L. The therapeutic results of T-ALL are also characterized by less frequency of corticosensitivity, complete remission, OS, and EFS. Although, there is less frequency of a relapse. Our results are compared to those in the literature. Keywords: ALL, Acute lymphoblastic leukemia, Phenotype, Children
P1211: TUMOR-ACTIVATED LYMPH NODE FIBROBLASTS SUPPRESS T CELL FUNCTION IN DIFFUSE LARGE B CELL LYMPHOMA
Authors: Benedetta Apollonio, Filomena Spada, Nedyalko Petrov, Domenico Cozzetto, Peter Jarvis, Despoina Papazoglou, Shichina Kannambath, Manuela Terranova-Barberio, Rose-Marie Amini, Gunilla Enblad, Charlotte Graham, Reuben Benjamin, Elizabeth H. Phillips, Richard Ellis, Rosamond Nuamah, Mansoor Saqi, Dinis Calado, Richard Rosenquist, Lesley Ann Sutton, Jon Salisbury, Georgios Zacharioudakis, Anna Vardi, Patrick Hagner, Anita Gandhi, Marina Bacac, Christina Claus, Pablo Umana, Ruth Jarrett, Christian Klein, Alexander Deutsch, Alan Ramsay
Journal: HemaSphere (2023)

Topic: 20. Lymphoma Biology & Translational Research Background: Recent transcriptomic-based analysis of diffuse large B cell lymphoma (DLBCL) has highlighted the clinical relevance of lymph node (LN) fibroblast and tumor-infiltrating lymphocyte (TIL) signatures within the tumor microenvironment (TME). However, the immunomodulatory role of fibroblasts in lymphoma remains unclear. Aims: LN fibroblasts (or fibroblastic reticular cells, FRCs) are specialized immune-interacting fibroblasts, that provide the highways for immune cells to migrate along and crucially regulate innate and adaptive immune responses. The aim of this study was to unmask the phenotypical, transcriptional and functional changes in FRCs following chronic exposure to DLBCL. Methods: We employed imaging mass cytometry, confocal microscopy, co-culture and organotypic functional assays to study DLBCL patient samples and a mouse model of disease. Results: Here, by studying human and mouse DLBCL-LNs, we identify the presence of an aberrantly remodeled fibroblastic reticular cell (FRC) network, expressing elevated fibroblast activated protein (FAP). RNA-sequencing analyses reveal that exposure to DLBCL reprograms key immunoregulatory pathways in FRCs, including a switch from homeostatic to inflammatory chemokine expression and elevated antigen presentation molecules. Functional assays show that DLBCL-activated FRCs (DLBCL-FRCs) hinder optimal TIL and chimeric antigen receptor T cell (CAR-T) migration. Moreover, DLBCL-FRCs inhibited CD8+ TIL cytotoxicity in an antigen-specific manner. Notably, the interrogation of patient LNs with imaging mass cytometry identified distinct environments differing in their CD8+ TIL-FRC composition and spatial organization that associated with survival outcomes. We further demonstrate the potential to target inhibitory FRCs to rejuvenate interacting TILs. Co-treating organotypic cultures with FAP-targeted immunostimulatory drugs and a bispecific antibody (glofitamab) augmented anti-lymphoma TIL cytotoxicity. Summary/Conclusion: Together, our study reveals an immunosuppressive role of FRCs in DLBCL, with implications for immune evasion, disease pathogenesis and optimizing immunotherapy for patients. Keywords: Diffuse large B cell lymphoma, Immunotherapy, Microenvironment, Tumor immunology
P1259: HUMAN UMBILICAL CORD MESENCHYMAL STEM CELLS AMELIORATE ACUTE GRAFT VERSUS HOST DISEASE BY ELEVATING PHYTOSPHINGOSINE
Authors: Guancui Yang, Rui Wang, Tao Hong, Xiaoqi Wang, Lingyu Zeng, Shijie Yang, Jin Wei, Qiangguo Gao, XI Zhang
Journal: HemaSphere (2023)

Topic: 21. Stem cell transplantation - Experimental Background: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an effective treatment for malignant hematological diseases. However, acute graft-versus-host disease (aGVHD) is currently the main complication limiting the wide application of transplantation. Human umbilical cord mesenchymal stem cells (HUCMSCs) have the potential to cure and prevent aGVHD because of their immunoregulatory activity and low immunogenicity. Metabolic imaging is being increasingly used in the clinic and may be useful in the posttransplantation setting for early noninvasive detection of GVHD. Phytosphingosine (PHS) is an effective metabolism in exerting anti-inflammatory activities, as well as the ability to regulate glucolipid metabolism. Aims: To evaluate whether HUCMSCs can alleviate aGVHD by regulating metabolism PHS and find the preliminary mechanisms of PHS to further provide new avenues for the prophylaxis or treatment of aGVHD. Methods: Lethally irradiated BALB/c were transplanted with C57BL/6 bone marrow (BM) with or without splenocytes, and HUCMSCs were intravenously treated to aGVHD mice. Survivals at different time points were recorded post-transplantation. LC–MS provides precise information on the metabolomics levels between aGVHD and HUCMSCs groups. After PHS treatment, the CD4+ T-helper 1 (Th1) cell differentiation were analyzed by flow cytometry. The protective effect of PHS was verified in vivo by i.p. administration to aGVHD mice. Results: We collected serum from the two groups (aGVHD and HUCMSC groups) of mice and performed LC–MS/MS to analyze all samples the on day 14. We found that PHS was significantly downregulated in the aGVHD group and elevated in the HUCMSC group (Figure 1A). Then 3.6 mg/kg and 7.2 mg/kg PHS in saline were administered via intraperitoneal injection to aGVHD mice every other day from day 3 to day 21 after transplantation, and the control group was given saline-DMSO injections. The data showed that aGVHD mice treated with high-dose PHS (7.2 mg/kg) exhibited significantly prolonged survival than untreated aGVHD mice (Figures B). We next examined the effect of PHS on Th1 cell differentiation in naive CD4+ T cells. In the presence of IL-2, IL-12 and anti-IL-4, stimulated naive CD4+ T cells in the DMSO group exhibited typical Th1 cell differentiation, with high IFN-γ and TNF-α expression and low IL-4 expression compared with cells in the negative control group, while the PHS group showed significant decreases in these Th1 inflammatory cytokines compared with the DMSO group (Figures 1C). Summary/Conclusion: In conclusion, HUCMSC infusion alleviated murine aGVHD and influenced metabolism by elevating PHS expression. PHS exhibited anti-inflammatory effects on the inhibition of Th1 cell differentiation, thus showing a protective effect in murine aGVHD.Keywords: HSCT, Graft-versus-host disease (GVHD)
P548: PRELIMINARY RESULTS OF A PHASE 1, FIRST-IN-HUMAN STUDY OF INA03, AN ANTI-CD71 ANTIBODY-DRUG CONJUGATE IN PATIENTS WITH RELAPSED OR REFRACTORY (R/R) ACUTE LEUKEMIAS
Authors: Sylvain Garciaz, Pierre Bories, Leonor Lopez Almeida, Jean-Marie Boher, Coralie Belanger, Christian Recher, Olivier Hermine, Norbert Vey, Pierre Launay
Journal: HemaSphere (2023)

Background: R/R acute leukemias (AL) represent major therapeutic challenges. Several reports have highlighted the role of iron metabolism in various proliferative tumor models including AL including the over-expression of the transferrin receptor (TfR1/CD71). Our strategy is thus to harness CD71 overexpression to specifically target cytotoxic agents to leukemic cells. INA03 is an antibody drug conjugate (ADC) constituted of a humanized monoclonal IgG4 against CD71 and the microtubule disrupting agent monomethyl auristatin E (MMAE). Aims: To report the preliminary safety and efficacy data of INA03 from a phase 1/2 trial in patients (pts) with R/R AL (NCT03957915). Methods: INA03 is given as 30 minutes IV infusion on days 1 (Loading dose (LD)) followed by maintenance injections on D15 for cycle 1 and on D1 and D15 of cycle 2 and beyond. Eligibility criteria are: R/R AL after at least one line of treatment including high dose chemotherapy and/or Vidaza and Venetoclax, AlloSCT >18y, with FEVG>50%, Creatinine Clearance >30ml/min, normal liver function, ECOG<2. The study design is based on a continuous reassessment method and includes 2 parts: a LD Titration study (Part 1, completed), followed by a Dose Escalation Part 2. During Part 1, sequential cohorts of 2 pts were included to receive ascending LD of INA03 followed by subsequent fixed dose of INA03 to deal with a potential sink effect related to the high expression of CD71 in normal erythroblasts. During Part 2, sequential cohorts of 3 pts received escalating doses of INA03 Q2 weeks in 28-day cycles. The objectives were to establish the MTD for subsequent administration and both safety/tolerability and anti-leukemic activity. Results: With a cutoff date of January 18, 2023, 22 pts across 8 cohorts were included in the study. The median age was 73 (range: 39 – 83), 20 (91%) pts had AML and two (9%) had ALL. Three (13.6%) pts had a prior allo-SCT and 12 (54.5%) had prior VEN exposure. Pts received escalating doses of INA03 of 0.02 mg/kg to 2 mg/kg. MMAE pharmacokinetics (PK) appears dose-proportional with a small accumulation after repeated IV, while INA03 PK exhibits target-mediated drug disposition without accumulation. No DLT was observed among the 18 DLT-evaluable pts, up to the highest dose of 2 mg/kg. No grade 2-4 TEAEs were observed. One related grade 1 TEAE (hyperkalemia/phosphatemia) was reported. Transient decrease of reticulocyte count and erythroblasts percentage were observed at 0.5 mg/kg and above. Blasts reductions >50% were seen in 3/18 evaluable pts at dose > 1 mg/kg including two partial responses. Summary/Conclusion: INA03 is well tolerated up to the dose of 2 mg/kg with some efficacy signals in R/R AL. The trial continues to accrue patients. Keywords: Acute leukemia, Phase I, Transferrin receptor, AML
P342: RAS PATHWAY ACTIVATION REMODELS THE BONE MARROW MICROENVIRONMENT IN ACUTE LYMPHOBLASTIC LEUKAEMIA
Authors: Mauricio Ferrao Blanco, Lennart Kester, Jayne Hehir-Kwa, Monique den Boer, Olaf Heidenreich, Josef Vormoor
Journal: HemaSphere (2023)

Background: Previous genomic profiling have identified somatic alterations in RAS pathway genes that drive treatment resistance in B-cell acute lymphoblastic leukaemia (B-ALL). Emerging evidence suggests that the bone marrow microenvironment is remodelled by malignant cells. However, how RAS activation drives leukemic progression and affects the communication with and the composition of the micro-environment is poorly understood. Aims: To identify whether RAS pathway activating mutations affect the cellular composition in the bone marrow in B-ALL using diagnostic RNA-seq data Methods: RNA-seq was generated from bone marrow mononuclear cells of pediatric B-ALL patients entering our center (n=210). Genomic analysis consisted of calling hotspot mutations in RAS pathway genes (KRAS, NRAS, BRAF and PTPN11), differential gene expression analysis, gene set enrichment analysis and cell type deconvolution. Results: RAS pathway mutations were found in 42% of patients, with 32% carrying them in a major clone (variant allele frequency > 25%). Frequent alterations in RAS pathway genes were identified in high-hyperdiploid (72%; n = 75) and ZNF384-rearranged (80%; n = 5), while rare in DUX4-rearranged (14%; n = 7) and TCF3-PBX1 (9%; n = 11) and absent in BCR-ABL leukemia (n = 6). Most recurrent lesions were found in NRAS (15%, n= 37) and KRAS (13%, n= 32), followed by mutations in PTPN11 (5%, n=15) and BRAF (1%, n= 3). The percentage of blasts relative to bone marrow mononuclear cells was not altered by the presence of RAS pathway mutations. Transcriptomic analysis was performed in the B-ALL cohort, comparing clonal RAS pathway mutations (n= 62) versus wild type cases (n= 123). Gene ontology analysis revealed attenuated immune response in samples harboring RAS mutations. This finding was corroborated by Cybersort analysis, observing a reduction in T cell numbers and decreased expression of the T cell marker genes CD3E, CD8B and CD4. Furthermore, pathway analysis highlighted interferon gamma signaling, a key trigger of CD8 T cell activation and differentiation, to be downregulated in RAS mutant cases. Interestingly, the expression of bone morphogenic protein 3 (BMP3), a member of the transforming growth factor-β (TGF-β) super-family which has been implicated in reducing the inflammatory response, was upregulated in RAS mutant samples. We are now using single-cell transcriptomics to validate these findings and further unravel the cell-cell communication network in the RAS-driven leukemic niche. Summary/Conclusion: RAS signalling reshapes the bone marrow immune-microenvironment, towards an immune suppressive niche. Our results suggest that the high expression levels of BMP3 may lead to a decrease in the inflammatory milieu in RAS pathway mutant leukaemia’s, which in turn attenuate T cell activation. Keywords: Bone marrow niche, Acute lymphoblastic leukemia
P957: AN INDIRECT COMPARISON OF ELRANATAMAB’S (ELRA) OBJECTIVE RESPONSE RATE (ORR) FROM MAGNETISMM-3 (MM-3) VERSUS REAL-WORLD EXTERNAL CONTROL ARMS IN TRIPLE-CLASS REFRACTORY (TCR) MULTIPLE MYELOMA (MM)
Authors: Luciano Costa, Thomas W Leblanc, Hans Tesch, Pieter Sonneveld, Ryan Kyle, Liliya Sinyavskaya, Patrick Hlavacek, Aster Meche, Jinma Ren, Alex Schepart, Didem Aydin, Marco Dibonaventura
Journal: HemaSphere (2023)

Topic: 14. Myeloma and other monoclonal gammopathies - Clinical Background: ELRA is a BCMAxCD3 bispecific antibody being investigated for the treatment of R/R MM. Aims: The phase 2 MM-3 trial was single-armed; the aim of this study (NCT05565391) was to contextualize the efficacy data from MM-3 with two real-world (RW) external control arms. Methods: A retrospective cohort study was conducted to indirectly compare the efficacy observed in MM-3 Cohort A (BCMA-naïve; N=123) from the 9-month data cut with two US-based oncology electronic health record databases, Flatiron Health (FH) and COTA, as external controls. MM-3 inclusion (eg, prior MM diagnosis, ECOG≤2, refractory to ≥1 PI, ≥1 IMiD, and ≥1 anti-CD38) and exclusion (I/E) criteria (eg, plasma cell leukemia, smoldering MM) were applied to each RW database to obtain comparable patient populations across sources. After imposing MM-3 I/E criteria, comparisons between data sources on ORR were conducted by estimating rate ratios (RRs) using log-binomial regression models (unweighted analysis). RRs were also estimated using both inverse probability treatment weighting (IPTW) and augmented IPTW (doubly robust) analyses to account for key covariates (eg, age, comorbidities, ECOG, ISS, prior lines/refractoriness, cytogenetic risk, extramedullary disease, lab values). Results: The 123 patients from MM-3 Cohort A were compared with the 152 and 233 patients identified from the FH and COTA databases, respectively. Treatment regimens in the RWD sources included various combinations of PIs, IMiDs, and mAbs, among other agents (eg, selinexor). Across unweighted, IPTW, and doubly robust analyses, the ORR for ELRA was significantly higher than treatments used for TCR MM patients from RWD sources (Table 1; all p<.05). Summary/Conclusion: Among TCR MM patients who resemble those of the MM-3 trial, ELRA showed improved ORR compared with treatments currently used in clinical practice.Keywords: Multiple myeloma, Myeloma, Real world data